Plastic composition



latented Sept. 5, 11922 UNITED STATES LINWOOD r, RICHARDSON, ormnwauxnawrscousm, assrenon -ro inn 0mm.-

HAMMER MFG. 00., O1 MILWAUKEE, WISCONSIN, A. CORPORATION OF WISCONSIN.

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No Drawing.

To all whom it may concern:

Be it known that I, ARDSON, a citizen of the United States,-residing atMilwaukee, in the county of Milwaukee and State of Wisconsin, haveinvented new and useful Improvements in Plastic Compositions, of whichthe following is a vents therefor, such, for example, as the compositionproposed in the patent to William H. Steinberg No. 1,233,416, of July17, 1917. I

In the manufacture of such compositions I have found that the use ofbinder-constituents containing fatty materials tends to lessen the waterresisting properties of the product, while on the other hand, certainconstituents ofthis class, such as stearin pitch, have properties whichrender the use thereof otherwise very desirable. For example, the use ofstearin pitch as set forth in the Steinberg patent, tends to increasethe hardness, density and mechanical strength of the product.

Further, I have found that in compositions of the aforesaid characterwherein the filler employed contains basic substances, the tendencymentioned is largely due to the re- "action of the fatty materials withsuch basic substances, and the present invention has among its objectsto curtail the loss of water resisting properties of the product fromthis cause. Also, theinvention has among its objects to provide a heattreatment for the product which will further minimize such tendency ofthe fatty materials of the binder constituents.

Compositions made in accordance with the present invention may comprisevarious alternative constituents, but it is preferred to employ thoseproposed in the Steinberg patent, and for the purpose of more fully andclearly explaining the present invention the production of a compositionfrom such constituents will now be described.

.Following the Steinberg patent, it 1s pro- LINWOOD T. R101?Application-filed December 24, 1917. Serial No. 208,538.

posed to use a filler comprising a mixture of comminuted asbestos andsulphur and a binder formed by mixing coal tar pitch and stearin pitchin, the-presence ofheat (400 to 500 F.) for precipitation of the freecarbon thereof, then, while the mixture is 'hot, adding thereto ananimal or vegetable oil, ca-

PATENT" OFFICE.

pable of vulcanization or polymerization,

preferably castor oil, then drawing off and cooling the supernatentfluid and finally adding thereto a benzol. f

However, it is now proposed to subject the asbestos to one of thefollowing alternative treatments or to some other treatment for thepurpose hereinafter set' forth, before using the same.

(a) subjecting the asbestos to the action of an acid, suchashydrochloric acid, whereby the basicity thereof is neutralized with theformation of soluble salts, then washing the asbestos with water forremoval of the soluble salts and finally drying the asbestos.

(b) subjecting the asbestos to an acid, such as phosphoric acid, forformation of insoluble salts, and then drying the same.

(a) Mixing the asbestos with a body cavolatile solvent, preferably pableof furnishing silicic acid (ground flint,

infusorial earth orprecipitated silicic acid) is probable that the sameresult might be accomplished in other ways. For instance, theelimination or neutralization of the basic substances in the asbestoscould doubtlessly be accomplished by subjecting the latter to the actionof various gases, such as carbon dioxide, or sulphur dioxide.

After such treatment of the asbestos it is proposed to mix the sulphurtherewith by any convenient method and to then mix the filler and binderpreferably in a cold state, as proposed in said Steinberg patent, toproduce a granular but plastic compound to be molded.

Finally it is proposed to heat treat the molded product to increase theheat resisting properties thereof; the degree of heat employed for suchtreatment being regulated according to the final heat resistance desiredof the product. Also, it is proposed to so heat treat the product in anatmosphere of steam or other non-oxidizing gas inert toward the same,the gas or steam being utilized to protect the product from access ofair, especially at elevated temperatures of 250 F. or more. And in thisconnection it it to be understood that this heat-curing step is distinctfrom and additional to the aforesaid treatment of the asbestos prior tomixing.

Further, it is to be understood that the proposed heat treatment mightbe omitted and that the product might be finally treated in other ways,as by the baking step previously used. However, the proposed heat'treatment is recommended as the wet strength curve of the product willthen very closely approximate the dry strength curve .of the product ifbaked, whereas the baking process tends to curtail the wet strength ofthe product. Also, the proposed treatment tends to increase the heatresistance of the product.

\Vhat I claim as new and desire to secure by Letters Patent is:

1. The herein described process, for curtailment of the effect of wateron plastic compositions formed of a binder containing fatty materialsand a filler containing basic ingredients, consisting in subjecting thefiller, prior to mixture with the binder, to a neutralizing treatmentrendering the filler ingredients non-combining as regards the fattymaterials of the binder.

2. The herein described process, for ourtailment of the effect of wateron plastic coinposltions formed of a binder containing fatty materialsand a filler containing basic ingredients consisting in mixing with thefiller a body capable of furnishing silicic acid and.

subjecting such mixture to steam under pressure, prior to mixing thebinder and tiller.

3. The herein described process, for plastic compositions formed of abinder containing fatty materials and a filler containmg basicingredient-s, consisting in subjecting the filler to a treatment forrenderin its ingredients non-combining with the fatty materials of thebinder, then mixing the filler and binder, and finally heat treating theproduct in an atmosphere of gas inert toward the product.

4. A composition of the character set forth comprising a binder havingstearin pitch as an ingredient thereof, and a filler of asbestos treatedto withstand the reactive eifects of the fatty material of said binder,said composition being heat treated in an atmosphere of inert gas forincreased resistance to the effect of water.

In witness whereof, I have hereunto subscribed my name.

LINWOOD T. RICHARDSON.

